Question

which of the following were states that were added to the union after the gold rush years?
texas and arizona
washington and oregon
nevada and colorado

Explanation:

The California Gold Rush occurred 1848-1855. Texas joined the Union in 1845 (before the Gold Rush), Arizona in 1912. Washington joined in 1889, Oregon in 1859 (both after the Gold Rush). Nevada joined in 1864, Colorado in 1876 (both after, but the key is identifying the correct pair. Oregon and Washington were part of post-Gold Rush western expansion statehood).

Answer:

Washington and Oregon